Fluid by-pass for rotary drill bits



Oct. 24, 1961 E, H. CLARK, JR., ETAL 3,005,507

FLUID BY-PASS FOR ROTARY DRILL BITS 4 Sheets-Sheet 1 Filed Sept. 50,1957 INVENTORS. Ema/57 E C1. 22%, 21?.

MAL/4M 0. MA /Q5 24, 1961 E. H CLARK, JR., ET AL 3,005,507

FLUID BY-PASS FOR ROTARY DRILL BITS Filed Sept. 30, 1957 4 Sheets-Sheet4 mum/14 D. M Ees INVENTORS aymvhjhum United States Patent FLUID BY-PASSFOR ROTARY DRILL BITS Earnest H. Clark, Jr,, Downey, and William D,Myers,

fl w l ali as ign s, by mes e a i t to Houston Oil Field MaterialCompany, Inc, Houston,

Tex., a corporation of Delaware Filed Sept. 30, 1957, Ser. No. 687,21516 Claims. (Cl. 175-324) The present invention relates to the drillingof well bores by the rotary method in which drilling mud is circulatedthrough the drilling string and drill bit.

Certain types of rotary drill bits used in the drilling of well borescontain nozzles or outlet openings of relatively small areas, in orderto discharge the drilling fluid, such as drilling mud, at acomparatively high velocity directly towards the bottom of the hole, orthe drill bit cutters, or both. The relatively small area of theopenings through the drill bit nozzles restricts the flow of thedrilling mud in the well bore into the tubular drilling string while itis being lowered in the well bore. In some situations, such restrictionresults in damage to the formation, caused by the drilling string andbit building up a comparatively high pressure in the drilling mud andforcing or ramming it into the formation.

Not only does the restricted fluid circulation area through the drillbit produce the aforesaid undesirable elfect, but it also decreases thefacility with which the drilling mud can drain from the drill pipe orother drilling string while being removed from the well bore. The resultis often the pulling of a wet job; that is, the spilling of the drillingmud on the derrick floor when a stand of drill pipe is beingdisconnected. This presents a hazardous condition at the working area tothe rig crew. It also results in the drill pipe performing a swabbingaction in the well bore while being elevated therein, with the danger.of a blow-out.

An object of the present invention is to provide an apparatus whichprevents the drilling string and bit from developing a high pressure inthe well bore drill ng mud while the drilling string and bit are beingrun in the well bore.

Another object of the invention is to provide an apparatus whichprevents the drilling string from swabbing the well bore while beingelevated therein, or from pulling a wet job.

A further object of the invention is to provide an apparatus whichenables :the zflllld in the well here to bypass around the drill bitinto the drilling string while the latter is being lowered in the wellbore, such bypassing being prevented while drilling fluid is beingpumped through the string in the performance of the drilling operation.

An additional object of the invention is to provide ,an apparatus whichenables the fluid in the well bore to bypass around .the drill bit fromthe interior of the drill bit to its exterior during elevation of thedrilling string in the well bore.

This invention possesses :many other advantages, and has other objectswhich may be made more clearly ap parent from aconsideration ofseveralforms in which it may be embodied. Such forms are shown in the drawingsaccompanying and forming part of the present specification. These formswill now be described in detail, for the purpose of illustrating thegeneral principles of :the invention; but it is to be understood thatsuch detailedidescription is .not to be taken in a limiting sense, sincethe scope of .the invention ,is best defined 'by the appended ,claims.

Referring ,to the drawings: FIGURE .1 is a longitudinal sect-ion throughan embodiment oftheepparatus, with the side ports open;

lowered in the well bore,

3,0055%? Patented Oct. 24, 196i HQ: 2. s n en r d i a m nta longitudinaltion of the apparatus shown in FIG. 1, with the side Ports close FIG, 3isa fragmentary cross-section on an enlarged scale taken along the line37 3 on FIG. 1;

FIG. 4 is a view similar to FIG, 1 of another embodiment of theinvention;

FIG. 5 is an enlarged longitudinal section of the apparatus shown inFIG. 4, with the by-pass portion thereof losed;

FIG. 6 is a cross-section taken along the line 66 on IG- :5;

FIG. 7 is a view similar to FIG. 1 of still another embodiment of theinvention;

FIG. 8 is an enlarged longitudinal section of the apparatus shown inFIG. 7, with parts in another relative position;

FIG. 9 is a cross-section taken along the line FIG. 8;

FIG. 10 is a longitudinal section taken along the line 1(l10 on FIG. 2;

FIG. 11 is a cross-section taken along the line 1111 on FIG. 2.

As disclosed in the drawings, a rotary drill bit A is connected to th lwer end of a string of drill pipe B, or similar tubular drilling string,that extends to the top of the hole. While the drilling string and drillbit are being rotated, drilling mud or the like is pumped down the drillstring, passing outwardly through discharge nozzles .C in the drill bitfor action upon the drill bit cutters D, or directly upon the bottom ofthe well bore being produced, In some types of drill bits, the areathrough the nozzles is relatively small, to cause the fluid issuingtherefrom to have a comparatively high velocity and impart a jetting orblasting action upon the bottom f the hole or the cutters, or both,which is conducive drilling action of the drill bit in the .....c H .MUh.

to more effective Well bore.

The relatively small area through the drill bit nozzles ,C restrictsthepassage of the drilling mud in the well bore into the stringY-ofdrill pipe B while it is being producing a substantial back pressure inthe drilling mud which is exerted upon ,the walls of the formation.Under some conditions, Such pressure may be sufficiently high as toactually break down the formation, with a consequent loss of drillingmud thereinto, or permanent damage to at producing formation.

The restricted fluid passage area through the drill bit also retards therate at which fluid can drain from the drill string B when the latter isbeing removed from the well bore, sometimes resulting in a swabbingaction by the drill bit on the fluid in the well bore of an extent.suflicient to produce ablow-out. In addition, the inability of ,thedrilling mud level to lower rapidly enough in the drill string, Whilethe latter is being removed from the well bore, results in drilling mudstill beingpresent in the stand of pipe above the rotary table when suchstand of pipe is being disconnected from the drill p p h ebelew, t e i nmud dr p 1 of the S and of drill pipe onto the derrick floor.

;I n the several'forrns of inventions illustrated in the drawings, theabove noted undesired characteristics of employing a drill bit withrestricted nozzle or passage areas therein is prevented. As disclosed inFIG. 1, the drill bit body 10 is threadedly secured to an annular body 11of a fluid by-pass apparatus E, as, for example, by having the upperthreaded pin '12 of the bit screwed into a lower threaded box 13 of thebody. The upper drill pipe extends to the top of the well bore in aknown manner.

The body 11 of the fluid by-pass apparatus is provided with a pluralityof circumferentially spaced side ports 16 extending completely throughits wall. The outer portion of the body surrounding each port may becounterbored to provide an enlarged port region 17 into which a screen18 is inserted and attached to the body in any suitable manner, asthrough use of welding material 19. The cross-sectional area of eachby-pass port 17 is relatively large, but each of the holes 20 throughthe screen is relatively small to prevent relatively large particlesfrom passing from the exterior of the apparatus through the ports 16 tothe interior thereof.

Disposed within the body 11 and extending across and on opposite sidesof the body ports 17 is an inner sleeve member 21 snugly engaging theinner cylindrical wall 22 of the body, with its lower end engaging theupper end of the pin 12 of the bit body 10. This sleeve 21 has acircumferential groove 23 in its exterior which communicates with thebody ports 17, and it also has a plurality of circumferentially spacedside ports 24 opening into the circumferential groove 23 and theinterior of the sleeve 21 itself. The inner sleeve has guide portions 25projecting inwardly of its adjacent ported regions, which function as aguide for the lower portion or valve head 26 of a control sleeve 27slidable longitudinally in the by-pass body 11. This control sleeve 27extends upwardly to a substantial extent above the upper end of theinner sleeve 21 and terminates at its upper portion in an annular piston28, the periphery of which is slidable along the inner wall 22 of thebody.

The control sleeve 27 has an opening or passage 29 extendingtherethrough of a diameter substtantially less than the minimum diameterthrough the inner sleeve 21. The diameter of the interrupted cylindricalsurface of the guide portions 25 is greater than the passage diameterthrough the control sleeve 27, but substantially less than the insidediameter of the inner Wall 22. The upper or annular piston portion 28 ofthe control sleeve carries a piston ring 31 in a ring groove 31 whichslidingly and sealingly engages the inner wall 22 of the body 11. Thisring will prevent downward passage of fluid between the piston and theinner wall of the body.

The control sleeve 27 is initially held in an upward position, with itspiston 28 engaging a downwardly facing stop shoulder 32 on the body andwith the lower end 33 of the control sleeve above the inner sleeve ports24, by a helical compression spring 34 surrounding the control sleeve,its lower end bearing against the upper end of the inner sleeve 21 andits upper end bearing against the piston 28. This spring may exert asubstantial force tending to keep the control sleeve 27 in its upperposition illustrated in FIG. 2, in which the sleeve ports 24 are open.For example, the spring 34 may be sutrlciently heavy as to exert a forceof about 300 pounds upon the control sleeve 27 tending to hold it in itsupward position.

When the inner sleeve 21 and control sleeve 27 are out of the body 11,the parts are maintained in assembled relation with the spring 34compressed by the engagement of an upwardly directed shoulder 35 on thecontrol sleeve 27 with a plurality of screws 36 threaded in the upperportion of the inner sleeve 21 and extending inwardly of the innersleeve over the stop shoulder 35 on the control sleeve. In view of sucharrangement, the control sleeve 27 and inner sleeve 21, with the spring34 compressed therebetween, can be inserted as a unit into the by-passbody 11 from its lower end, after which the threading of the drill bit Ainto the lower portion of the body will force the inner sleeve 21upwardly to a slight extent and will definitely locate thecircumferential groove 23 of the inner sleeve in alignment with theby-pass ports 16 through the main body member 11.

The control sleeve 27 is shifitable downwardly completely across theports 24 until its valve head 33 engages a companion valve seat 37provided in the inner sleeve. The engaging surfaces between the head 33and seat 37 may be tapered, if desired. To insure proper sealingengagement between the valve head and its companion seat, arcuate reliefgrooves 38 are provided through the lower end of the guide portions 25,along which the valve head 33 slides, into which particles and the likecan be forced during the seating of the valve head against its companionseat 37.

In the operation of the apparatus illustrated, the spring 34 tends tokeep the control sleeve 27 in its upper position, in which the sleeveports 24 are open. Accordingly, as the string of drill pipe B, with thedrill bit A attached to its lower end, is lowered through the drillingmud or other fluid in the well bore, the fluid will enter the drillstring through the drill bit nozzles C. It will also enter the drillstring through the by-pass apparatus E, fiovn'ng through the screenopenings 20 and the bypass ports 16 into the circumferential groove 23,thence inwardly through the sleeve ports 24 to the interior of thesleeve '21 and then upwardly through the central passage 29 in thecontrol sleeve 27 into the drill pipe B thereabove. The externalhydrostatic head can also act on the underside of the piston portion 28since the fluid in the annular space between the control sleeve 27 andthe inner wall 22 of the body is always communicable with the ports 16.In the FIG. 1 position, fluid can pass from the ports 16, groove 23 andaround the valve head 26 into such annular space. The same is true whenthe valve head 26 engages the seat 37, as shown in FIG. 2. The minimumarea of the passage just described may be made rather large, to permitthe drilling mud in the well bore to flow rather freely into the drillpipe B, and to minimize the building up of pressure in the. fluid in thewell bore as a result of lowering the string of drill pipe therewithin.

When the drill pipe B has been run in the well bore and the drillingaction is to commence, the drilling mud is pumped down through the drillpipe B. The passage 29 through the control sleeve 27 has a lesserdiameter than the pass-age through the drill pipe thereabove, whichdevelops a back pressure on the control sleeve 27 suflicient in extentto overcome the compression of the spring 34 and shift the controlsleeve downwardly until its valve head 33 engages its companion seat 37(FIG. 2). So long as fluid is being pumped at a suflicient volumetricrate through the drill pipe B to provide the necessary pressure on thepiston 28, the control sleeve 27 will be held in its downward positionin engagement with the valve seat 37, to close the sleeve port 24, andthereby prevent any of the drilling mud from passing laterally throughthe by-pass apparatus E to the exterior of the drill pipe B.Accordingly, all of the drilling mud pumped down through the string ofdrill pipe B must pass through the drill bit A and through its nozzlesC, issuing therefrom at the desired high velocity to impose a jetting orblasting action on the bottom of the well bore, or the drill bitcutters, in order to keep the bottom and cutters free of cuttings.

Not only is the back pressure built up above the control sleeve 27effective to hold it in a downward position closing the sleeve ports 24,but the control sleeve provides a differential area which adds to thehydraulic force tending to hold the control sleeve in its lowerposition. When the control "sleeve engages the valve seat 37, theeffective area R across the lower end of the control sleeve 27, overwhich fluid pressure can act and tending to urge the control sleeve inan upward direction, is much less than the etfective area S of theannular piston 28 over which the fluid pressure is acting and tending toshift and hold the control sleeve in a downward direction. In view ofthe difierential area relationship, even if the unit pressure above andbelow the control sleeve 27 were equal, the latter would still be urgedin a downward direction against the force of thespring 34 and retainedin engagement with the valve seat 37 to close the sleeve ports 24.

sponsor .So long as drilling mud is being pumped down through the drillpipe B, the control sleeve 27 will remain in its lower position closingthe ports 24, insuring that .all of the equal external and internalhydrostatic heads of fluid are acting over equal and opposite areas S ofthe sleeve valve 27, the spring 34 need not overcome any substantialpressure differentials and can readily elevate the sleeve to portopening position. Accordingly, during elevation and removal of the drillpipe from the well here, the fluid can drain from the drill pipe Bthrough the nozzles C of the drill bit, but a large and major portion ofsuch fluid can also drain through the sleeve ports 24, circumferentialgroove 23, by-pass ports 16-and screen openings 20 to the exterior ofthe bit. The drill pipe is thereby drained in a rapid manner during itsremoval the well bore, which minimizes the swabbing action of the stringof drill pipe on the fluid in the well bore as the pipe is beingelevated therewithin, and which also insures that the stand of pipeabove the rotary table will be in a dry state upon its disconnectionfrom the string of drill pipe therebelow.

If it is desired to remove the internal mechanism of the lay-passapparatus B, such action can occur very simply by disconnecting thedrill bit A from the body 11, the spring 34 expanding slightly to engagethe stop screws 36 with the control sleeve .shoulder 35, whereupon theinner-sleeve 21, control sleeve 27 and the spring 34 can be removedsafely and as .a unit from the body.

In the embodiment of the invention illustrated in FIGS. 4, and 6, themain tubular body 11a is connected to the upper end 12 of the drill bitA, as before, with its upper end 14a threadedly secured to the adjacentsection of drill pipe or drill collar B. A tubular body member 40 ismounted centrally in the passage .of the body 11a, and hascircumferentially spaced, radial arms 41 extending therefrom to theinner wall 42 of the main body member. There are arcuate passages 43defined between the tubular body member 11a, radial arms 41 and innerwall 42 of the main body, through which the drilling fluid can pass. Thetubular body member 40 has a central passage 44 extending from its openupper end to a lower end wall 45. This central passage 44 communicateswith ports or passages 46 formed in nozzle members 47 threaded withincompanion threaded holes 48 in-the main body 1111 of the apparatus, theinner portion .of these nozzle members extending radial bores 49 in theradial arms 41, so that there is communication between the exterior ofthe main body 11a and the central passage 44 in the tubular body member40. Leakage of fluid between the nozzles 47 and the body member 11a canbe prevented by suitable side seal rings 50 mounted in the nozzles.

Because .of the radial passages 46 and the central passage 44 in thetubular body member 49, drilling fluid in the swell bore can flowinwardly throughthe nozzles into the central passage and then into themain body 11a. As explained hereinbelow, the drilling mud in the stringof drill .pipe B, under some conditions, can also flow in a reversedirection from the interior of the main body 11a to itsexterior. Duringthe actualdrilling :oper- .ation, it lie-desired to prevent the drillingfluid from flowing downwardly through the central passage 44 and outthrough the radial :ports 46 in .the nozzles 47. A device :above thetubular body member 4.0 is provided in the main body 11a to accomplishthis result.

.As disclosed, the upper end .of the tubular body memher 40 is formed asa valve .seat .51 adapted to be ento a valve stem 53 which extendsupwardly through the lower cylinder head 54 0f a cylinder :55. Thecylinder includes a skirt 56 threaded onto the head 54 and .extendingupwardly therefrom, the upper end of the skirt being open. The cylinderskin 56 has circumferentially spaced centering ribs 57 extendingtherefrom, which engage an outer sleeve 58, snugly fitting the innercylindrical wall 42 of the main .body -11a of the tool. The cylinder 55and sleeve 58 are secured to the main body by a plurality of radialscrews 59 threaded in the main body member 11a and into the outer sleeve58 and ribs 57. Arcuate passages 60 are formed between the ribs 57., thecylinder sleeve portion .56 and the outer sleeve 58 through whichdrilling mud can pass in .both directions through the apparatus. 7

A piston .61 is .slidable in the cylinder 55, being secured to the upperend of the valve stem 53. This piston has a piston ring 62, in the formof a rubber or rubber-like member, mounted thereon which slidably andsealingly engages the inner --wall of the cylinder 55. This seal ring.62 is adapted to prevent downward passage of fluid between the piston61 and the cylinder wall. The piston 61, stem 53 and valve head 52 areurged in an upward direction with respect to the cylinder .55 by ahelical compression spring .63 in the cylinder bearing against the lowercylinder head .54 land the piston 61 itself. One or more ports 64 areprovided in the lower portion of the cylinder sleeve 56 to providecommunication between the cylinder 55 .on .the lower sideof the piston61 and one or more of the longitudinally extending arcuate passages 60 Ithrough the valve apparatus.

In the use of the apparatus disclosed in FIGS. 4, 5 and 6, the spring 63normally maintains the valve head 52 in an upward position substantiallyremoved from its companion valve seat 51 therebelow. The lowering of thestring of drill pipe B, with the drill :bit A attached thereto, throughthe drilling mud or other fluid in the well .bore, will not only allowsuch drilling fluid to flow through the drill bit nozzles into thestring of drill pipe B, but also permits the drilling fluid in the wellbore to flow through the nozzle ports 46 into the central passage 44,discharging through its upper valve seat '51 into the body 11a of thetool and mingling with the drilling mud that enters .the body 11athrough the drill bit A for up ward flow through .the arcuate passages60 in the valve structure and into the drill pipe sections thereabove.The area .of the nozzle ports '46 and the .central passage 44 are quitesubstantial, to permit the ready ingress of a large quantity of the Wellbore fluid into e string of drill pipe, and preventing the building upof any substantial pressures in the drilling mud in the well bore duriugthe lowering of the drill pipe IB and drill bit A there- Within.

When the drill bit is .to operate upon the bottom of the hole, thedrilling mud 'is pumped down through the drilling string ,B. Thepressure of the drilling mud will act on the piston 61 and move itdownwardly against the force of the spring 63 to engage the valve head52 with its companion seat 51, closing the central passage 44.Accordingly, all of the drilling mud must then flow through the 'arcuatepassages 43 around the tubular body member 40 and enter the drill bit,discharging from its nozzles at a high velocity. All of the drilling mudpumped down the drill string passes out .through the drill .bit A toperforrm the desired purposes in the well bore.

Not only is a back pressure built up on the upper surface of the piston61 to urge itand hold 'itdownwardly, to secure the valve head 52 againstthe companion valve .seat 51,1butthe how of the drilling mud through thearcuate passages 60 in the valve stnucturepast the -lower ports reducesthe pressure of the'fluid in the cylinder below will urge the piston 61,valve stem 53 and valve head 52 downwardly to maintain the valve head 52engaged with its companion seat 51.

After the drilling operation with the bit A has been completed and it isdesired to remove the string of drill pipe B from the well bore, thepumping of the drilling mud ceases, which then permits the spring 63 toraise the piston 61, stem 53 and valve head 52 and remove the latterfrom engagement with its seat 51. As the drill pipe is being removedfrom the well bore, the drilling mud can drain therefrom, not onlythrough the drill bit nozzles but also through the open central passage44 and the side ports 46 in the by-pass apparatus.

In the form of inventions disclosed in FIGS. 7, 8 and 9, essentially thesame tubular body member and nozzle arrangement is employed as in theform of invention illustrated in FIGS. '4, and 6. However, in lieu ofthe cen tral passage 44a through the tubular body member 40a beingclosed by a piston operated valve structure, the tubular body member isprovided with a valve seat 70 therewithin engageable by a ball valveelement 71 when the latter moves downwardly within the body 40a. Thecentral passage 44a in the tubular body member has a greater diameterabove the valve seat 70 than the ball valve element 71, to permit thelatter to move longitudinally in the tubular body member towardengagement with the valve seat 70 and upwardly away from engage mentwith the valve seat. Upward movement of the valve element 71 is limitedby its engagement with radial stop pins 72 disposed in upwardlyextending arms 73 of the tubular body member and projecting into itspassage 44a. In view of the provision of the circum'ferentially spacedarms 73, by-pass openings 74 are provided therebetween through which thedrilling mud can pass when the ball valve element 71 is raised from itsseat 70 and when it engages the stop pins 72.

With the apparatus disclosed in FIGS. 7, 8 and 9, the lowering of thestring of drill pipe B and drill bit A in the well bore will permit thedrilling mud in the well bore to flow upwardly through the drill bitnozzles into the main body 11b of the apparatus, then passing throughthe arcuate passages 43 to the upper portion of the main body. Drillingfluid can also flow through the ports 46 in the nozzles 47 into thecentral passage 44a, carrying the ball valve element 71 upwardly to theextent limited by its engagement with the stop pins 72, and then flowingoutwardly through the bypass openings 74, continuing on into the drillpipe sections B thereabove.

When the drilling operation is to be performed, the drilling mud ispumped down through the string of drill pipe B and will move the ballvalve element 71 downwardly into engagement with its valve seat 70,holding it in such engagement. As a result, the by-pass ports 46, 44aare closed, and all of the drilling mud must flow down through thearcuate passages 43 into the drill bit A to discharge from its nozzlm.

When it is desired to remove the drill pipe B from the well bore, theball valve element 71 will remain seated, so that no part of thedrilling mud in the string of drill pipe can drain outwardly through theports 46 in the nozzles 47. To secure an increased drainage area fromthe string of drill pipe, a plurality of drain side ports 80 areprovided in the main body 11b of the apparatus above the tubular bodymember 40a. These drain ports 80 are normally closed by a sleeve valve81 disposed thereacross, this sleeve valve being provided with suitableside seal rings 82 on opposite sides of the drain ports to preventleakage therearound. The sleeve valve is retained in this positionacross the ports 80 by one or more shear screws 83 threaded into themain body 11b, with its inner portion disposed within a circumferentialgroove 84 in the sleeve 81. The sleeve valve 81 has an inner passage 85therethrough of a comparatively large diameter, so as not to restrictthe passage of fluid through 1 the string of drill pipe. The upperportion of this passage is surrounded by a valve seat 86 adapted to beengaged by a vavle element 87 in the form of a ball. This ball valveelement is normally not present in the drill string B, but is onlydropped or pumped through the drill string when the latter is to beremoved from the well bore. Upon engaging its seat 86 it will close thepassage 85 through the sleeve valve 81, allowing pressure to be built upin the fluid thereabove to a suflicient extent as to shear the screws 83and shift the sleeve valve 81 and ball 87 downwardly to a position belowthe drain ports 80. The sleeve valve 81 will come to rest on the upperend of the tubular body member 44a (FIG. 8). The fluid in the drill pipewill now drain out through the drain ports 80, which collectively have acomparatively large area to permit the drainage to occur at a fairlyrapid rate.

It is, accordingly, apparent that by-pass apparatus for use inconjunction with a rotary drill bit has been provided which assures theready ingress and egress of drilling mud with respect to the interior ofthe string of drill pipe. The by-pass ports are only opened during therunning of the string of drill pipe in the well bore and its removaltherefrom. The by-pass ports are closed during the actual drillingoperation to insure that all of the drilling mud is discharged throughthe drill bit nozzles for effective jetting or blasting action upon thebottom of the well bore, or upon the cutters, or both.

The inventors claim:

1. In drilling apparatus for a well bore: a tubular drill string; adrillbit secured to the drill string and having a nozzle for dischargingfluid from the drill string; said drill string having a side port in itslower portion above said bit for allowing fluid to flow between theinterior and exterior of said drill string; valve means shiftable toport closing position in response to downward pumping of fluid throughthe drill string, said valve means including means responsive topressure externally of said drill string to equalize the hydrostatichead of fluid internally of the drill string and tending to shift saidvalve means from port closing position to port opening position and alsotending to hold said valve means in port opening position; and springmeans engaging said valve means to shift said valve means to portopening position; said spring means exerting a force sufiicient tomaintain said valve means in port opening position during elevation ofsaid drill string and drill bit in the well bore to permit simultaneousdrainage of drilling fluid from said drill string through said port andbit nozzle.

2. A drilling apparatus for a well bore: a tubular drill string; a drillbit secured to the drill string and having a nozzle for dischargingfluid from the drill string, said nozzle being normally open to permitfluid to flow upwardly therethrough into the drill string duringlowering of the drill string in the well bore and said drill stringbeing open to permit such upward flow of fluid therewithin; said drillstring having a side port in its lower portion above said bit forallowing fluid to flow between the interior and exterior of said drillstring; a sleeve valve having a passage therethrough and slidable insaid drill string across said port to close the same in response todownward flow of fluid in the drill string, said sleeve valve includingmeans responsive to pressure externally of said drill string to equalizethe hydrostatic head of fluid internally of the drill string and tendingto shift said sleeve valve from port closing to port opening positionand also tending to hold said sleeve valve in port opening position; andmeans for shifting said sleeve valve to port opening position upondecrease of the downward flow of fluid in the drill string; saidshifting means exerting a force on said sleeve valve suflicient tomaintain said sleeve valve in port opening position during elevation ofsaid drill string and drill bit in the well bore to permit simultaneousdrainage of drilling fluid from said drill string through said port andbit nozzle.

3. A drilling apparatus for a well bore: a tubular drill ass- ,50?

string; a drill bit secured to the drill string and having a nozzle fordischarging fluid from thedrillstring, said nozzle being normally opento permit fluid to flow upwardly therethrough into the drill stringduring lowering of the drill string in the well bore and said drillstring being open to permit such upward How of fluid therewithin; saiddrill string having a side port in its lower portion above said bit forallowing fluid to flow between the interior and exterior of said drillstring; a sleeve valve having a passage therethrough and slidabledownwardly in said drill string and across said port to close the samein response to downward flow of fluid in the drill string, said sleevevalve including means responsive to pressure externally of said drillstring to equalize the hydrostatic head of fluid internally of the drillstring and tending to shift said sleeve valve from port closing to portopening position and also tending to hold said sleeve valve in portopening position; and spring means engaging said sleeve valve to shiftit upwardly in said drill string to port opening position upondiminution in the downward flow of fluid in the drill. string; saidspring means exerting a force suflicient to maintain said sleeve valvein port opening position during elevation of said drill string and drilldrill bit in the well bore to permit simultaneous drainage of drillingfluid from said drill string through said port and bit nozzle.

4. A drilling apparatus for a well borez. atubular drill string; a drillbit secured to the drill string and having a nozzle for dischargingfluid from the drill string; said drill string having a first side portin its lower portion above said bit for allowing fluid to flow betweenthe interior and exterior of said drill string; a sleeve in said drillstring disposed across said firstside port and having a second side portcommunicating with said first side port; a sleeve valve having a passagetherethrough and slidable in said drill string and sleeve across saidsecond port to close the same in response to downward flow of fluid inthe drill string, said sleeve valveincluding means responsive topressure externally of said drill string to equalize the hydrostatichead of fluid internally of the drill string; and tending to shift saidsleeve valve from port closing to port opening position and also tendingtohold said sleeve valve in port opening position; and means forshifting said sleeve valve to port opening position upon decrease in thedownward flow of fiuid' in the drill string; said shifting meansexerting a force on saidsleeve val ve suflicient to maintain saidsleeve'valve in port opening position during elevation of said drillstring and drill bit in the well bore to permit simultaneous drainage ofdrilling fluid from said drill string through saidport and bit nozzle.

5. A drilling apparatus for a well bore: a tubular drill string; a drillbit secured to the drill string and having a nozzle for dischargingfluid from the drill string; said drill string having a first side portin its lower portion above said bit for allowing fluid to flow betweenthe interior and exterior of said d'rill string; a sleeve. in said drillstring disposed across said first sid'eport and having a second sideport communicatingwith said first side port;'a sleeve valvehavingapassage therethrough and slidable downwardl'y in said drill string andsleeve across: said second side port toclose the same inre'sponse todownwardflow of fluidin the drill string, saidsl'e'eve valveincludingmeans responsive to: pressure externally of said drill string toequalize the hydrostatic head of fluid internally of the drill stringand tending to shift said sleeve valve from port closing to port openingposition and also tending to:hold

said sleeve valve in port opening position; and spring means engagingsaid sleeve valve and sleeve to shift said sleeve valveupwardly in saiddrill string to port opening position upon diminution of the downwardflow of fluid in the drill' string; said spring means exerting aforce-suffl'cient to maintain said sleeve valve in port opening positionduring elevation of said drill string and drill bit in the well bore topermit simultaneous drainage of drilling fluid fro'm said drill stringthroughsaidport and bitlnozzlev 6. A drilling apparatus for a well bore:a; tubular drill string; a drill bit secured to the drill string andhaving a nozzle for discharging fluid from the drill string; said drillstring having a first side port in its lower portion above said. bit forallowing fluidto flow between the interior and exterior of said drillstring; a sleeve in said drill string disposed across: said first sideport and having a second side port communicating with said firstsideport; a sleeve valve having a passage therethrough and slidabledownwardly in said drill string and sleeve across said second side portto close the same in response to downward flow of fluid in the drillstring, said sleeve valve including means responsive to pressureexternally of said drill string to equalize the hydrostatic head offluid internally of the drill string and tending to shift said sleevevalve from port closing to port opening position and also tending tohold said sleeve valve in port opening position; spring means engagingsaid sleeve valve and sleeve to shift said sleeve valve upwardly in saiddrill string to port opening position upon diminution of the downwardflow of fluid in the drill string; said spring means exerting a forcesufficient to maintain said sleeve valve in port opening position duringelevation of said drill string and drill bit in the well bore to penrnitsimultaneous drainage of drilling fluid from said drill string throughsaid port and bit nozzle; and coengageable stop means on said sleeve andsleeve valve to limit upward movement of said sleeve valve relative tosaid sleeve.

7. In drilling apparatus for a well bore; a tubular body adapted to formpart of a string of drill pipe to be disposed in the well bore; saidbody having a side port for allowing flow of fluid between the interiorand exterior of the drill pipe; a sleeve valve having a passagetlierethrough and slidable in said body across said port to close thesame in response to downward flow of fluid in the tubular body, saidsleeve valve including means responsive to pressure externally of saidbody to equalize the hydrostatic head of fluid internally of the bodyand tending to shift said sleeve valve from port closing to port openingposition and also tending to hold said sleeve valve in port openingposition; and means for shifting said sleeve valve to port openingposition upon decrease of the downward flow of fluid in said body; saidshifting means exerting a force on said sleeve valve suflicient tomaintain said sleeve valve in port opening position during elevation ofsaid tubular body and drill string in the Well bore to permit drainageof drilling fluid from the drill string through said port.

8-. In drilling apparatus for a well bore: a tubular body adapted toform part of a string of drill pipe to be disposed in the well bore;said body having a side port for allowing flow of fluid between theinterior and exterior of the drill pipe; a sleeve valve having a passagetherethrough and slidable downwardly in said body across said port toclose the same in response to downward flow of fluid in said body, saidsleeve valve including means responsive to pressure externally of saidbody to equalize the hydrostatic head of fluid internally of the bodyand tending to shift said sleeve valve from port closing to port openingposition and also tending to hold said sleeve valve in port openingposition; and spring means engaging said sleeve valve to shift itupwardly in said body to port opening position upon diminution in thedownward flow of fluid in said body, said spring means exerting a forcesuflicient to maintain said sleeve valve in port opening position duringelevation of said bodyand drill string in the well bore and to permitdrainage of drilling fluid from the drillstring posed acrosssaid; firstside port and having a second side port communicating with said firstside port; a sleeve valve having a passage therethrough and slidable insaid body and sleeve across said second side port to close the same inresponse to downward flow of fluid in said body, said sleeve valveincluding means responsive to pressure externally of said body toequalize the hydrostatic head of fluid internally of the body andtending to shift said sleeve valve from port closing to port openingposition and also tending to hold said sleeve valve in port openingposition; and means for shifting said sleeve valve to port openingposition upon decrease in the downward flow of fluid in said body; saidshifting means exerting a force on said sleeve v-alve suflicient tomaintain said sleeve valve in port opening position during elevation ofsaid drill string and drill bit in the well bore to permit simultaneousdrainage of drilling fluid from said drill string through said port andbit nozzle.

10. In drilling apparatus for a well bore: a tubular body adapted toform part of a string of drill pipe to be disposed in the well bore;said body having a first side port forallowing flow of fluid between theinterior and exterior of the drill pipe; a sleeve in said body disposedacross said first side port and having a second side port communicatingwith said first side port; a sleeve valve having a passage therethroughand slidable in said body and sleeve across said second side port toclose the same in response to downward flow of fluid in said body, saidsleeve valve including means responsive to pressure externally of saidbody to equalize the hydrostatic head of fluid internally of the bodyand tending to shift said sleeve valve from port closing to port openingposition and also tending to hold said sleeve valve in port openingposition; and spring means engaging said sleeve valve and sleeve toshift said sleeve valve upwardly in said body to port opening positionupon diminution in the downward flow of fluid in said body; said springmeans exerting a force suflicient to maintain said sleeve valve in portopening position during elevation of said drill string and drill bit inthe Well bore to permit simultaneous drainage of drilling fluid fromsaid dn'll string through said port and bit nozzle.

11. In drilling apparatus for a well bore: a tubular body adapted toform part of a string of drill pipe to be disposed in the well bore;said body having a first side port for allowing flow of fluid betweenthe interior and exterior of the drill pipe; a sleeve in said bodydisposed across said first side port and having a second side portcommunicating with said first side port; a sleeve valve having a passagetherethrough and slidable in said body and sleeve across said secondside port to close the same in response to downward flow of fluid insaid body, said sleeve valve including means responsive to pressureexternally of said body to equalize the hydrostatic head of fluidinternally of the body and tending to shift said sleeve valve from portclosing to port opening position and also tending to hold said sleevevalve in port opening position; spring means engaging said sleeve valveand sleeve to shift said sleeve valve upwardly in said body to portopening position upon diminution in the downward flow of fluid in saidbody; said spring means exerting a force sufficient to maintain saidsleeve valve in port opening position during elevation of said drillstring and drill bit in the Well bore to permit simultaneous drainage ofdrilling fluid from said drill string through said port and bit nozzle;and coengageable stop means on said sleeve and sleeve valve to limitupward movement of said sleeve valve relative to said sleeve.

12. In drilling apparatus for a well bore: a tubular drill string; adrill bit secured to the drill string and having a nozzle fordischarging fluid from the drill string, said nozzle being normally opento permit fluid to flow upwardly therethrough into the drill stringduring lowering of the drill string in the well bore and said drillstring being open to permit such upward flow of fluid therewithin; saiddrill string having a side port in its lower portion above said bit forallowing fluid to flow between the interior and exterior of said drillstring; a valve seat below said port; a sleeve valve having a passagetherethrough and slidable in said drill string across said port intoengagement with said valve seat to close said port in response todownward flow of fluid in the drill string, said sleeve valve havingtransverse fluid pressure actuatable surfaces; means providing fluidcommunication between said surfaces and the pressure fluid externallyand internally of said drill string when said sleeve valve is in portopening and port closing positions; and means for shifting said sleevevalve to port opening position upon decrease of the downward flow offluid in the drill string; said shifting means exerting a force on saidsleeve valve sufllcient to maintain said sleeve valve in port openingposition during elevation of said drill string and drill bit in the wellbore to permit simultaneous drainage of drilling fluid from said drillstring through said port and bit nozzle.

13. In drilling apparatus for a well bore: a tubular drill string; adrill bit secured to the drill string and having a nozzle fordischarging fluid from said drill string, said nozzle being normallyopen to permit fluid to flow upwardly therethrough into the drill stringduring lowering of the drill string in the well bore and said drillstring being open to permit such upward flow of fluid therewithin; saiddrill string having a side port in its lower portion above said bit forallowing fluid to flow between the interior and exterior of said drillstring; a sleeve valve having a passage therethrough and slid able insaid drill string across said port to close the same in response todownward flow of fluid in the drill string said sleeve valve havingtransverse fluid pressure actuatable surfaces; means providing fluidcommunication between said surfaces and the pressure fluid internallyand externally of said drill string when said valve seat is in portopening and port closing positions; and means for shifting said sleevevalve to port opening position upon decrease of the downward flow offluid in the drill string; said shifting means exerting a force onsaid'sleeve valve suflicient to maintain said sleeve valve in portopening position during elevation of said drill string and drill bit inthe well bore to permit simultaneous drainage of drilling fluid fromsaid drill string through said port and bit nozzle.

14. In drilling apparatus for a well bore: a tubular member adapted toform part of a string of drill pipe to be disposed in the well bore;said body having a side port for allowing flow of fluid between theinterior and the exterior of the drill pipe; a valve seat below saidport; a sleeve valve having a passage therethrough and slidable in saidbody across said port into engagement with said valve seat to close saidport in response to downward flow of fluid in the tubular body, saidsleeve valve having transverse fluid pressure actuatable surf-aces;means providing fluid communication between said surfaces and thepressure fluid internally and externally of said tubular body when saidvalve seat is in port opening and port closing positions; and means forshifting said sleeve valve to port opening position upon decrease of thedownward flow of fluid in said body; said shifting means exerting aforce on said sleeve valve suflicient to maintain said sleeve valve inport openingposition during elevation of said drill string and drill bitin the well bore to permit simultaneous drainage of drilling fluid fromsaid drill string through said port and bit nozzle.

15. In drilling apparatus for a well bore: a tubular body adapted toform part of a string of drill pipe to be disposed in the well bore;said body having a side port for allowing flow of fluid between theinterior and exterior of the drill pipe; a sleeve valve having a passagetherethrough and slidable in said body across said port to close'thesame in response to downward flow of fluid in the tubular body, saidsleeve valve having transverse fluid pressure actuatable surfaces; meansproviding fluid communication between said surfaces and the pressurefluid internally and externally of said tubular body when said sleevevalve is in port opening and port closing positions; and means forshifting said sleeve valve to port opening position upon decrease of thedownward flow of fluid in said tubular body; said shifting meansexerting a force on said sleeve valve sufiicient to maintain said sleevevalve in port opening position during elevation of said drill string anddrill bit in the well bore to permit simultaneous drainage of drillingfluid from said drill string through said port and bit nozzle.

16. In drilling apparatus for a well bore: a tubular drill string; adrill bit secured to the drill string and having a nozzle fordischarging fluid from the drill string, said nozzle being normally opento permit fluid to flow upwardly therethrough into the drill stringduring lowering of the drill string in the Well bore and said drillstring being open to permit said upward flow of fluid therewithin; asleeve valve having a passage therethrough and an enlarged upper pistonportion slidable along the drill string and above said port and a lowerpiston portion of less external diameter than the upper piston portionslidable along the drill string and across said port to close the samewhen said upper and lower portions are subject to downward flow of fluidin the drill string; means providing fluid communication between thepressure fluid externally of said drill string and the lower side ofsaid upper piston portion; and means for shifting said sleeve valve toport opening position upon decrease of the downward flow of fluid in thedrill string.

References Cited in the file of this patent UNITED STATES PATENTS1,867,832 Hill July 19, 1932 1,918,096 Greve July 11, 1933 2,198,487Sisk Apr. 23, 1940 2,211,846 Brown Aug. 20, 1940 2,363,290 Bridwell Nov.21, 1944 2,726,724 Wilhoit et a1. Dec. 13, 1955

